The present invention relates generally to a transmission control system for controlling a transmission having a plurality of gear positions. More particularly, the invention relates to a transmission control system suitable for an automated manual transmission.
An automated manual transmission (M/T) employs a mechanical clutch in place of a fluid clutch employed in an ordinary automatic transmission (A/T) to automatically manipulate a clutch for engaging and disengaging by means of an actuator. Such automated manual transmission is apt to be employed in some kinds of European sporty cars. In the automated manual transmission, a shift lever has the first speed gear position, second speed gear position, . . . sixth speed gear position and so forth, similarly to the ordinary manual transmission. A clutch operation of the driver in the conventional M/T is automated in such a manner that when a driver operates the shift lever, a shift control system detects the shifting operation, releases the clutch by controlling an actuator, shifts the gear positions, and then engages the clutch. On the other hand, the automated manual transmission also has a "Drive" (D) range position. In a period of holding at D range, engaging and disengaging of the clutch and shifting of the gear positions are performed automatically depending upon depression amount of an accelerator pedal and a vehicle speed, like shifting operation of an ordinary A/T.
As disclosed in JP-A-7-197955, automatic disengaging and engaging of the clutch is controlled by effecting an engine control for preventing the engine from causing stalling due to damping effect for forced operation of the clutch in such a manner that torque and engine revolution speed control in response to the shifting demand is performed by varying an output torque of the engine through a spark ignition timing, a fuel injection amount and an air flow rate of an induction air of the engine.
However, as disclosed in the above-identified JP-A-7-197955, in a system to perform the engine control in response to shifting operation, the engine is driven at engine operation parameter values far different from optimal values at a combustion demand in common engine control. As a counter effect, various problems, such as degradation of fuel economy, lowering of torque response, degradation of emission control performance and so forth can be caused.